Soil Fertility Improvement by Litter Decomposition and Inoculation with the Fungus Mortierella sp. in Avocado Plantations of Colombia

Litter decomposition is a major process in nutrient recycling, despite that few studies have considered this in soil fertility management. The aim of this study was to evaluate the effect of litter decomposition and its inoculation with the fungus Mortierella sp. on soil fertility parameters in Andisols cultivated with avocado cv. Hass. Litterbags containing avocado leaves either uninoculated or inoculated were distributed around the trees. As control litter was not allowed to accumulate on the soil surface. Eighteen months later soil samples were collected just below uninoculated and inoculated litterbags and control sites. Soil pH, potassium, calcium, phosphorus, magnesium, and boron significantly increased with litter and in some sites the increase was higher with inoculation. By contrast, soil aluminum, iron, and manganese were significantly lower in the presence of litter (uninoculated and inoculated), whereas zinc was significantly higher when litter was present.     

Biodegradability of Disinfectants in Surface Waters from Buenos Aires: Isolation of an Indigenous Strain Able to Degrade and Detoxify Benzalkonium Chloride

Biodegradability of chlorhexidine (CH), triclosan (TC), and benzalkonium chloride (CBA) has been tested in 18 surface water sampling points in the urban area of Buenos Aires. Sampling points were located in both the Reconquista and the Matanza-Riachuelo basins as well as in the La Plata River. High tolerance to the three disinfectants was found and indigenous strains capable of degrading CBA and TC were isolated. Neither tolerance nor biodegradation were correlated with sewage pollution. A strain that degrades CBA was identified as belonging to the genus Pseudomonas using the API20NE system and 16SRNA sequencing. In batch assays, the strain was capable of degrading 100, 200, and up to 500 mg L^?1 of CBA in 10, 25, and 46 h respectively with specific growth rates (μ) of 0.56, 0.30, and 0.14 h^?1. The efficiency of the process was between 99.5–98.0% in terms of compound removal and between 93.8–89.1% in terms of chemical oxygen demand (COD). The detoxification of the compound as a result of the biodegradation was assessed using Pseudokirchneriella subcapitata, Vibrio fischeri, and Lactuca sativa as test organisms.     

Technologies for the diagnosis and remediation of Fe deficiency

The objective of this paper is to review the developments in the last few years in two important issues related to Fe deficiency in plants. First, the current knowledge on the possible ways to carry out the diagnosis and prognosis of Fe deficiency in plants is discussed. This includes discussion on the best ways to carry out a meaningful analysis of Fe-containing compounds in different plant parts. We will also discuss other measurement techniques that can permit to assess the Fe nutritional status in plants, including leaf chlorophyll concentrations and others. Second, the new developments in management techniques to control and remediate iron deficiency are discussed. This includes possible improved ways to supply Fe compounds available to plants, both to the soil and to the irrigation water. We also discuss possible ways to supply directly the plant with Fe containing compounds, either to the foliage or to the stem. A particular emphasis is given throughout the paper to fruit tree crops growing in Mediterranean areas.     

Participatory organic certification in Mexico: an alternative approach to maintaining the integrity of the organic label

Over the past two decades the growth of the organic sector has been accompanied by a shift away from first party, or peer review, systems of certification and towards third party certification, in which a disinterested party is responsible for the development of organic standards and the verification of producer compliance. This paper explores some of the limitations of the third party certification model and presents the case of Mexico as an example of how an alternative form of participatory certification has emerged. The paper suggests that participatory guarantee systems (PGS) are reflective of the growing “beyond organic” movement, which focuses on reconstructing the local and re-embedding food systems into their socio-ecological contexts. It argues that PGS offers a number of benefits for producers and consumers, particularly in the South, but that it faces a number of challenges as well, such as a lack of formal recognition, social conflicts and dependence on donated resources.     

Recycling of Two-Phase Olive-Mill Cake “Alperujo” by Co-composting with Animal Manures

The use of poultry manure or goat/sheep manure in the co-composting of the two-phase olive-mill cake “alperujo” (ALP) with olive leaf (OL) is compared by studying organic-matter mineralization and humification processes during composting and the characteristics of the end products. For this, two different piles (P1 and P2) were prepared using ALP with OL mixed with poultry manure (PM) and goat/sheep manure (GSM), respectively, and composted by the turned windrow composting system. Throughout the composting process, a number of parameters were monitored, such as temperature, pH, electrical conductivity (EC), organic matter (OM), OM losses, total organic carbon (C_org), total nitrogen (N_t), C_org/N_t ratio, and the germination index (GI). In both piles, the temperature exceeded 55 °C for more than 2 weeks, which ensured maximum pathogen reduction. Organic-matter losses followed a first-order kinetic equation in both piles. The final composts presented a stabilized OM and absence of phytotoxins, as observed in the evolution and final values of the C_org/N_t ratio (C_org/N_t < 20) and the germination index (GI > 50 percent). Therefore, composting can be considered as an efficient treatment to recycle this type of waste, obtaining composts with suitable properties that can be safely used in agriculture.     

Identification of <Emphasis Type="Italic">Pythium tracheiphilum</Emphasis> as the causal agent of vascular necrosis of endive (<Emphasis Type="Italic">Cichorium endivia</Emphasis>) in Spain

Pythium isolates were recovered from endive plants (Cichorium endivia) showing vascular necrosis collected from commercial fields located in Castellón province (eastern Spain). They were identified as Pythium tracheiphilum on the basis of their phenotypical and molecular profile. Pathogenicity tests conducted with two P. tracheiphilum isolates, obtained from endive and lettuce (Lactuca sativa), respectively, in this region, confirmed that both isolates were pathogenic to endive, with no significant differences in virulence between them. This is the first report of vascular necrosis caused by P. tracheiphilum on endive in Spain.     

Prion protein gene polymorphism in four West African sheep populations

A total of 162 individuals, belonging to three Burkinabé and one Niger sheep populations, were analysed for prion protein (PrP) gene polymorphism at codons 136, 154 and 171. The ARQ allele was the most frequent in both the Burkinabé (86.7%) and the Niger (67.5%) sheep populations. The highly sensitive allele VRQ was not found in the sampled individuals. The highly resistant ARR allele was in very low frequency in the Burkina-Sahel (4.4%) and Mossi (3.2%) populations and was not present in the Djallonké and Touareg populations. Only 4 out of 15 possible PrP genotypes were identified in the sampled individuals. No favourable ARR/ARR genotypes were found in either of the breeds. Sequencing a subgroup of the samples allowed the identification of other five polymorphisms on the PrP gene sequence at codons 116, 138, 151, 237 and 240. The very low frequency of the ARR allele in the West African sheep should dissuade the implementation of a preventive selection programme aimed to increase resistance to scrapie, to avoid an extreme erosion of the genetic stock.